A large piezoelectric voltage coefficient in aluminate-sodalite-type improper ferroelectric oxides

Abstract

The dielectric and piezoelectric properties of aluminate-sodalite-type oxides, (Ca_1−xSr_x)₈[AlO₂]₁₂{MoO₄}₂ ((CS)AM-x), have been investigated in the present study. The variation of dielectric anomalies clarifies the phase diagram of (CS)AM-x over a composition range of x = 0.00–0.20 to suggest that a unique phase boundary like the morphotropic phase boundary (MPB) exists between x = 0.05 and 0.10. The piezoelectric voltage coefficient g₃₃ at room temperature has been found to culminate around the phase boundary with the value being greater than that for the conventional lead-free perovskite-type ferroelectric oxides. The present result sheds light on the development of eco-friendly piezoelectric-active materials with excellent functionalities.